A local leader named Nan Lü (남려) walked into a Han camp with a petition and three carts of names, and the scroll said 280,000 people asked to join Han. The officers froze, because whole towns had just picked a new ruler in a single day.
Nan Lü was an official inside 고조선 who rebelled against the Wiman court and then offered his people to the Han emperor. The number is wild. Ancient Han records say he handed over 280,000 people, men, women, kids, all at once. That kind of mass transfer looked less like diplomacy and more like a city switching teams mid-game.
Emperor Wu of Han set up a new commandery called 창해군 to hold the gain. It sounds like a fresh victory, but it barely lasted. The new office was far from Han supply lines, local loyalties flipped back, and within a few years Han scrapped the post. The episode shows that a written surrender does not buy control, it buys a headache.
The bigger showdown came later, when Wiman's dynasty under King 우거 dug in and clashed with Han envoys. In 108 BC Han sent a big invasion and wiped out Wiman rule. After the war Han planted four commanderies, including 낙랑군, that reshaped politics and trade on the peninsula for centuries.
What surprises most is how messy diplomacy was, full of local bargains, mass surrenders, and quick reversals. People, not treaties, often decided which state would hold the land that week.
Borders back then were cheap to change when a leader could hand over 280,000 people on a scroll. Text that to someone who thinks borders are forever.